1. Field of the Invention
The present invention relates to preparation method of lubricating oil and lubricating oil produced thereby. More particularly, the present invention relates to preparation method of lubricating oil and lubricating oil produced thereby, which has excellent extreme pressure load resistance and wear resistance properties.
2. Discussion of Related Art
Typically, lubricating oil should have an appropriate viscosity at its operating temperature, have a small change in the viscosity in response to a change in the operating temperature, form a stable oil film even in the boundary lubrication, and have a high stability to heat and oxidation.
However, recently, due to high performance, high power, and large scale of various lubrication and lubrication devices, the operating load and temperature are increased, and thus the durability of the device and lubricating oil is reduced and the frequency of failures increases.
A nano-lubricating oil provided by the present invention is prepared by mixing an existing oil with a metal alloy oxide or non-metal nanoparticles and an extremely small amount of dispersant, which allows the metal alloy oxide or non-metal nanoparticles to be well dispersed in a colloid state, and it was confirmed that the nano-lubricating oil has a significant effect on the reduction in the coefficient of friction and the oil temperature.
This has been actually applied to vehicle engine oils and, recently, extensive research aimed at applying such lubricating oils to gear oil, cutting oil, and the like has continued to progress.
For example, in the case of the gear oil, in order to improve the extreme pressure properties, an attempt to improve the friction, wear, and lubricating properties by pulverizing tungsten disulfide (WS2) or molybdenum disulfide (MoS2), which is conventionally used as a solid lubricant, to nanoparticles as it is and dispersing the nanoparticles into the lubricating oil have been extensively made in the related industry. However, the specific gravity of the material is too high to improve the dispersibility, and an increase in the cost limits the commercialization. Recently, an attempt to reduce the specific gravity of the material by the formation of fullerene-like structure is made; however, satisfactory results are not obtained in terms of the size of the synthesized powder and the dispersibility. The reason is that when the nanopowder added to the lubricating oil is precipitated, the nanopowder does not act as an additive any longer, but acts as an impurity, thereby accelerating the deterioration of the material and its physical properties.
Moreover, a sufficient effect can be obtained even when an extremely small amount of nanopowder in a single composition is added for the purpose of reducing the coefficient of friction such as an engine oil additive. However, there are many difficulties in significantly improving both the load resistance and wear resistance properties of the lubricating oil under high load conditions. That is, the conditions for improving the load resistance properties of the lubricating oil and the conditions for improving the wear resistance properties of the powder do not coincide with each other, and thus there are many materials which maximize one of the properties. However, it is difficult to find a material which can maximize more than two properties at the same time.